Semiconductor device

ABSTRACT

A semiconductor device comprises at least a semiconductor module including a semiconductor chip, a heat sink thermally connected to the semiconductor chip and a seal member for covering and sealing the semiconductor chip and the heat sink in such a manner as to expose the heat radiation surface of the heat sink. The radiation surface is cooled by a refrigerant. An opening is formed in a part of the seal member as a refrigerant path through which the refrigerant flows.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.11/262,764 filed on Nov. 1, 2005, which is based on and claims priorityto Japanese Patent Application No. 2004-327670filed on Nov. 11, 2004,the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a semiconductor device comprising asemiconductor module fabricated by sealing a semiconductor elementconnected to a heat radiation metal plate of which a surface is cooledby a refrigerant, and also relates to a semiconductor device comprisinga stack of semiconductor modules.

2. Description of the Related Art

The semiconductor device of this type generally comprises asemiconductor module including at least a semiconductor element, atleast a metal plate thermally connected with the semiconductor elementto transmit the heat from the semiconductor element and a seal memberfor containing and sealing the semiconductor element and the metal platein such a manner as to expose the heat radiation surface of the metalplate. The radiation surface of the metal plate is cooled by arefrigerant.

This semiconductor device is so configured as to easily radiate the heatgenerated in the semiconductor element. Therefore, for example, thesemiconductor device is used for a power converter. In recent years,demand for a lower cost and a smaller size of this device has increased.

A conventional semiconductor device having a simple cooling structurefor heat radiation has been proposed, in which a semiconductor modulesealed with seal member are fixed at an upper wall and a bottom plate ina case to form a refrigerant path between semiconductor module and thecase, (see Japanese Unexamined Patent Publication No. 2004-119667.

However, the refrigerant paths of the conventional art are formedbetween the semiconductor module and the case and, therefore, the spacefor arranging the cases is required, thereby correspondingly increasingthe size of the device as compared with the semiconductor module.

SUMMARY OF THE INVENTION

In view of the above-mentioned problem, the object of this invention isto realize a compact, simple cooling structure in a semiconductor devicecomprising at least a semiconductor module including a semiconductorelement connected with a heat radiating metal plate, which is sealedwith a seal member, wherein the heat radiation surface of the metalplate is cooled by a refrigerant.

In order to achieve this object, according to this invention, there isprovided a semiconductor device comprising at least one semiconductormodule (1) including a semiconductor element (11, 12), a metal plate(20, 30) thermally connected with the semiconductor element (11, 12) fortransmitting the heat from the semiconductor element (11, 12) and a sealmember (50) for covering and sealing the semiconductor elements (11, 12)and the metal plate (20, 30) in such a manner as to expose the heatradiation surface (21, 31) of the metal plate (20, 30), wherein the heatradiation surface (21, 31) of the metal plate (20, 30) is cooled with arefrigerant, and wherein a part of the seal member (50) is formed as arefrigerant path (53) in which the refrigerant flows.

In view of the fact that a part of the seal member (50) of thesemiconductor module (1) is formed as the refrigerant path (53),additional parts such as a cooling tube and a case required in the priorart are eliminated, and therefore the semiconductor device can bereduced in size.

According to the present invention, a compact, simple cooling structurecan be realized in a semiconductor device comprising the semiconductormodule (1) including the semiconductor element (11, 12) connected to themetal plate (20, 30), which is sealed with the seal member (50), whereinthe radiation surfaces (21, 31) of the metal plate (20, 30) are cooledby the refrigerant.

The seal member (50) includes a sealing part (51) for sealing thesemiconductor element (11, 12) and the metal plate (20, 30) and the wallpart (52) arranged around the sealing part (51) and having an open endthereof positioned far from the radiation surface (21, 32) of the metalplate (20, 30). An opening (53) of the sealing part (51) is formed asthe refrigerant path between the metal plate (20, 30) and the wall part(52).

The wall part (52) can be arranged so as to surround the side of themetal plate (20, 30).

The seal member (50) includes the sealing part (51) for sealing thesemiconductor element (11, 12) and the metal plate (20, 30), and thewall part arranged around the sealing part (51) (52) having an open endthereof positioned far from the heat radiation surface (21, 31) of themetal plate (20, 30). An opening of the wall part (52) is formed as therefrigerant path.

The seal member (50) can be formed of resin.

The radiation surfaces (21, 31) of the metal plate (20, 30) may berough. The radiation surfaces (21, 31) of the metal plate (20, 30) mayhave at least one fin (83) projected from the same surface. By doing so,the heat radiation performance of the semiconductor module (1) can beimproved.

The heat radiation surface (21, 31) of the metal plate (20, 30) can beelectrically insulated from the semiconductor element (11, 12). By doingso, if the refrigerant is water or the like conductive material, thecircuit of the semiconductor element (11, 12) can be properly insulated.In this case, the heat radiation surface (21, 31) of the metal plate(20, 30) may be the surface of insulating layer (21 a, 31 a) formed onthe surface of the metal plate (20, 30).

The heat radiation surface (21, 31) of the metal plate (20, 30) may notbe electrically insulated. In the case where the refrigerant is anelectrically insulating material such as air or oil, it is not necessaryto insulate the heat radiation surfaces (21, 31) of the metal plate (20,30).

The inner wall surface of the refrigerant path can be covered with afilm (84) having a corrosion resistance against the refrigerant. Bydoing so, the corrosion resistance against the refrigerant is improvedadvantageously.

Electrode terminals for a main current (60) can be projected from oneside of the semiconductor module (1), and control terminals (70) can bearranged on the opposite side of the semiconductor module (1). Accordingto this invention, due to the absence of a case, the electrode terminals(60) and the control terminals (70) can be projected in two directionsfrom the two opposite sides of the semiconductor module (1).

In the conventional semiconductor device, projection of terminals in twoopposite directions would increase the sealing points of the bottomplate of the case and complicate both the structure and assembly work.Therefore, the terminals have been often led out only in one directionfrom the semiconductor module. Thus, the terminal wires have to bearranged in a space and the insulation distance among the terminal wirescannot be large. Therefore, to prevent this inconvenience, a device sizehas been unavoidably increased. According to one aspect of theinvention, in contrast, the terminals can be arranged in two directionsand therefore a more compact device can be obtained advantageously.

A plurality of the semiconductor modules (1) can be stacked andconnected while the respective refrigerant paths (53) can communicatewith each other. Also, the stacked semiconductor modules (1) can beconnected to each other while the respective refrigerant paths (53) cancommunicate with each other, and at the same time, each semiconductormodule (1) can be connected on the side or end surface of the wall part(52).

In the conventional semiconductor device configured of the stackedsemiconductor modules the following problem is posed. Specifically, inview of the fact that the cooling members such as the cooling tube forcooling the semiconductor modules are stacked with the semiconductormodules, the stack structure is configured of different types ofmembers. Therefore, a plurality of cooling tubes are required to beconnected and a multiplicity of liquid sealing points are required,thereby complicating the assembly work. Also, in order to keep thecooling members and the radiation surfaces of the metal plate in contactwith each other by pressing the cooling members against the radiationsurfaces of the metal plate, a pressure mechanism is required. Forexample, a contractible member such as a bellows must be arrangedbetween a plurality of the cooling members. This makes a device largeand complicates the structure. Also, in view of the fact that differenttypes of members including the semiconductor module and the coolingmember are stacked, the cumulative error between them increases and sodoes the thickness variations along the direction of the stack. Thisalso causes variations of the terminal positions of the semiconductormodule, thereby making it difficult to set in position the terminals formounting the semiconductor device on a circuit board.

To cope with this problem, a semiconductor device comprising the stackedsemiconductor modules according to aspects of the invention produces aunique effect described below. Specifically, since a part of the sealmember (50) of the semiconductor module (1) is formed as the refrigerantpath, the whole refrigerant path can be configured simply by connectingthe individual semiconductor modules (1). As a result, the pressuremechanism and the additional cooling members used in the prior art areeliminated, and the cooling structure can be easily realized. Also, thesemiconductor module (1) is produced by molding the seal member (50),and therefore, an outer dimensional accuracy very high or, for example,as high as ±0.1 mm or less can be easily achieved as compared with theprior art. Even in the case where a multiplicity of semiconductormodules (1) are connected, therefore, the positional accuracy of theterminals is improved over the prior art.

Further, the connecting surface of the wall part (53) has a positioningconcave or convex form, and therefore the wall parts (52) can beconnected easily to each other.

The wall parts (53) can be connected to each other by adhesive.

The stacked semiconductor modules (1) are arranged in such a manner thatthe radiation surfaces (21, 31) of the metal plate (20, 30) are placedopposite to each other and each has at least one fin projectingtherefrom (83). The relation can hold that hf<D, where hf is the heightof the fins (83) and D the height of the wall part (52) from theradiation surfaces (21, 31) of the metal plate (20, 30). Alternatively,the relation may be hf≥D, and the positions of the fins on the heatradiation surfaces (21, 31) differ between one of the heat radiationsurfaces and the other opposite heat radiation surface. In this case,the fins (83) are in the form of comb teeth projected from the radiationsurfaces (21, 31) of the metal plates (20, 30), and the fins (83) on theone of the radiation surfaces are placed between the fins (83) on theother opposite radiation surface. By doing so, the fins (83) formed onthe radiation surfaces (21, 31) of the metal plate (20, 30) in opposedrelation to each other of the stacked semiconductor modules (1) areadvantageously prevented from interfering with each other.

The side shape of the wall part of the seal member may be an invertedtrapezoid. The stacked semiconductor modules can be formed by bondingthe open ends of the wall parts to be communicated with all refrigerantpaths. In the case where the semiconductor device according to thisaspect of the invention is used as an inverter of a motor or the like,the similarity of the semiconductor device to the rotary machine such asthe motor can reduce the wiring distance, simplify the connections andeffectively reduces noise.

Also, the stacked semiconductor modules (1) can be configured as a powercircuit. A first bus bar (91) and a second bus bar (92) forming theinput connecting wires of the power circuit are preferably arranged inparallel and proximity to each other.

An insulating member (94) can be interposed between the first bus bar(91) and the second bus bar (92). Alternatively, the first bus bar (91)and the second bus bar (92) are covered and sealed by an insulatingmember (95). With the configuration of the semiconductor device usingthe insulating members (94, 95) according to these aspects of theinvention, the electrical insulation is secured between the first busbar (91) and the second bus bar (92) and, therefore, the intervalbetween the first bus bar (91) and the second bus bar (92) can bereduced, thereby making it possible to reduce both the device size andthe parasitic inductance of the wiring advantageously.

A semiconductor device according to the present invention can furthercomprise at least another component module sealed with a seal memberhaving a refrigerant part. The (85, 86, 87) can be stacked withcomponent module the semiconductor modules (1) and cooled together bythe refrigerant.

The metal plate (20, 30) of the semiconductor module (1) are arranged onat least one side of the semiconductor element (11, 12), and only thesurface of the metal plate (20, 30) formed on the one side of thesemiconductor element (11, 12) is exposed from the seal member (50).These exposed surface of the metal plate (20, 30) may be formed as theheat radiation surface (21, 31).

Visible surfaces of the stacked semiconductor modules (1) can form theprinting surfaces of the semiconductor modules (1). By doing so, even inthe stacked semiconductor modules (1), the printing surfaces can bechecked visually, and therefore the serial numbers, etc. can beadvantageously confirmed.

According to still another aspect of the invention, the stackedsemiconductor modules (1) are connected to each other by being heldunder the pressure by cover plates (80) arranged at the ends thereof.Each adjoining semiconductor modules (1) is kept in contact with anO-ring (8 a) so as to seal contact portions between the semiconductormodules (1). As a result, the refrigerant path is formed by contactpressure through the O-ring (82 a), and therefore, a defective module,if included in the plurality of the stacked semiconductor modules (1),can be easily replaced or repaired.

The reference numerals in the parentheses designating the componentelements described above indicate an example of correspondence with thespecific means included in the embodiments described later.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention willbecome clearer from the following description of the preferredembodiments given with reference to the attached drawings, wherein:

FIG. 1A is a perspective view schematically showing a semiconductordevice according to a first embodiment of the invention;

FIG. 1B is a sectional view taken in line A-A in FIG. 1A;

FIG. 2 is an enlarged sectional view schematically showing theneighborhood of the heat radiation surfaces according to a modificationof the first embodiment;

FIG. 3A shows a configuration of a semiconductor device comprising aplurality of semiconductor modules connected to each other according tothe first embodiment;

FIG. 3B is a sectional view taken in line B-B in FIG. 3A;

FIG. 4 is a perspective view schematically showing a semiconductordevice according to a second embodiment of the invention;

FIG. 5A is a diagram showing an example of the sectional configurationtaken in line C-C in FIG. 4;

FIG. 5B shows another example of the sectional configuration taken inline C-C in FIG. 4;

FIG. 6A is a perspective view showing a general configuration of asemiconductor device according to a third embodiment of the invention;

FIG. 6B is a side view taken along the arrow A′ in FIG. 6A;

FIG. 7A shows a configuration of a semiconductor device comprising aplurality of semiconductor modules connected to each other according tothe third embodiment;

FIG. 7B is a sectional view taken in line D-D in FIG. 7A;

FIG. 8 is a perspective view showing a semiconductor device according toa modification of the third embodiment;

FIG. 9 is a diagram showing a sectional configuration of a semiconductordevice according to a fourth embodiment of the invention;

FIG. 10A is a perspective view showing a general configuration of asemiconductor device according to a fifth embodiment of the invention;

FIG. 10B is a sectional view taken in line E-E in FIG. 10A;

FIG. 11 is a sectional view showing a general configuration of asemiconductor device comprising a plurality of semiconductor modulesconnected to each other according to the fifth embodiment;

FIG. 12 is a sectional view showing a general configuration of a powerconverter as a semiconductor device according to a sixth embodiment ofthe invention;

FIG. 13 is a diagram showing an equivalent circuit of the powerconverter of FIG. 12;

FIG. 14A is a front view showing the detailed wiring configuration ofthe semiconductor module of the power converter shown in FIG. 13;

FIG. 14B is a top plan view of the configuration shown in FIG. 14A;

FIG. 14C is a diagram showing an equivalent circuit;

FIG. 15A is a front view showing another example of the wiringconfiguration of the semiconductor module of the power converter shownin FIG. 13;

FIG. 15B is a top plan view of the configuration shown in FIG. 15A;

FIG. 15C is a diagram showing an equivalent circuit;

FIG. 16 is a diagram showing a first modification of the sixthembodiment; and

FIG. 17 is a diagram showing a second modification of the sixthembodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the invention are described below with reference to thedrawings. In each embodiment described below, the same or equivalentcomponent parts are designated by the same reference numerals,respectively, to simplify the explanation.

(First Embodiment)

FIG. 1A is a perspective view showing a general configuration of asemiconductor device 100 according to a first embodiment of theinvention. FIG. 1B is a diagram showing a sectional configuration alongthe one-dot chain line A-A in FIG. 1A.

As shown in FIGS. 1A, 1B, the semiconductor device 100 according to thisembodiment is mainly configured of a semiconductor module 1 a.

The semiconductor module 1 shown in FIGS. 1A, 1B includes a firstsemiconductor chip 11 and a second semiconductor chip 12 assemiconductor elements, a lower heat sink 20 as a first metal plate, anupper heat sink 30 as a second metal plate, solder 41, 42 as conductivejoint interposed between the semiconductor elements and the lower heatsink 20 or the upper heat sink 30, and a molded resin 50 as a sealmember.

In the semiconductor module 1 a according to this embodiment, as shownin FIGS. 1A and 1B, the first semiconductor chip 11 and the secondsemiconductor chip 12 are arranged in parallel to each other on a plane.Although two semiconductor elements are shown in FIG. 1B, only onesemiconductor element or three or more semiconductor elements mayalternatively be included.

In this configuration of the semiconductor module 1 a, the rear surfaces(lower surfaces in FIG. 1B) of the semiconductor chips 11, 12 and theupper surface of the lower heat sink 20 are joined to each other by thefirst solder 41.

Also, as shown in FIG. 1B, the front surfaces (upper surfaces in FIG.1B) of the semiconductor chips 11, 12 and the lower surface of the upperheat sink 30 are joined to each other by the second solder 42.

The lower parts of the upper heat sink 30 are projected to thesemiconductor chips 11, 12, and the projected part surfaces and theupper surfaces of the semiconductor chips 11, 12 are joined to eachother by the second solder 42, respectively.

In this upper heat sink 30, the function of the projected partsdescribed above, though not shown in FIGS. 1A, 1B, is to secure theheight of the bonding wires drawn from the semiconductor chips 11, 12.The projected parts also function to secure the height between thesemiconductor chips 11, 12 and the upper heat sink 30.

In place of the projected parts, independent heat sink blocks for thesemiconductor chips 11, 12 may be interposed between the upper surfacesof the semiconductor chips 11, 12 and the upper heat sink 30.

This heat sink blocks can be arranged through solder or the like, inwhich case the heat sink blocks function to secure the height betweenthe semiconductor chips 11, 12 and the upper heat sink 30.

According to this embodiment, any of the widely-used lead-free soldersuch as Sn—Pb or Sn—Ag solder can be used as the solder 41, 42.

As a result, in the configuration described above, heat is radiatedthrough the second solder 42 and the upper heat sink 30 on the frontsurfaces of the first and second semiconductor chips 11, 12, while heatis radiated through the first solder 41 and the lower heat sink 20 onthe rear surfaces of the first and second semiconductor chips 11, 12.

As described above, the lower heat sink 20 and the upper heat sink 30are formed with metal plates which are thermally connected to the firstand second semiconductor chips 11, 12, which are semiconductor elements,and transmit heat from the semiconductor chips 11, 12.

In the lower heat sink 20, the lower surface thereof in FIG. 1B is theheat radiation surface 21. In the upper heat sink 30, on the other hand,the upper surface thereof in FIG. 1B is the heat radiation surface 31.As shown in FIGS. 1A and 1B, the heat radiation surfaces 21, 31 areexposed from the molded resin 50 a.

The first semiconductor chip 11, though not specifically limited, canbe, for example, a power semiconductor element such as IGBT (insulatedgate bipolar transistor) or a thyristor.

Similarly, the second semiconductor chip 12 can be, for example, a FWD(free wheel diode). Specifically, the first and second semiconductorchips 11, 12 can have a shape of, for example, a rectangular thin plate.

Circuit elements such as transistors are formed on the front surfaces ofthe first and second semiconductor chips 11, 12 while no elements areformed on the rear surfaces thereof.

According to this embodiment, electrodes (not shown) are formed on thefront and rear surfaces of the first and second semiconductor chips 11,12. The electrodes are electrically connected to the solders 41, 42.

The electrodes on the rear surfaces of the first and secondsemiconductor chips 11, 12 are electrically connected to the lower heatsink 20, or the first metal plate, through the first solder 41, whilethe electrodes on the front surfaces of the first and secondsemiconductor chips 11, 12 are electrically connected to the upper heatsink 30, or the second metal plate, through the second solder 42.

The lower heat sink 20 and the upper heat sink 30 are made of metalhaving high in heat conductivity and electrical conductivity such as acopper alloy or an aluminum alloy. Also, the lower heat sink 20 and theupper heat sink 30 can be formed with a rectangular plate, for example.

Electrode terminals for main current 60 are integrated with the lowerheat sink 20 and the upper heat sink 30 and projected out of the moldedresin 50 a.

The electrode terminals 60 function as lead electrodes of thesemiconductor chips 11, 12, whereby the semiconductor device 100 can beconnected with external wiring such as a bus bar.

Thus, the lower heat sink 20 and the upper heat sink 30 are formed asthe first and second metal plates serving as an electrode as well as aheat radiator. That is, the lower heat sink 20 and the upper heat sink30 have the dual functions of radiating heat from the semiconductorchips 11, 12 and conducting electricity to the semiconductor chips 11,12 of the semiconductor device 100.

It is apparent that the thermal and electrical connection between thesemiconductor chips 11, 12 and the heat sinks 20, 30 is possible also byuse of a conductive adhesive or the like in place of the solder 41, 42.

The semiconductor module 1 a has also control terminals 70, which areformed of lead frames or the like around the semiconductor chips 11, 12.The control terminals 70 are hermetically fixed by the molded resin 50 aand each end of the terminals 70 is projected out of the molded resin50.

The end of each control terminal 70 can be connected electrically to,for example, an external control circuit board. Thus, the semiconductordevice 100 is electrically connected to the control circuit board.

The control terminals 70 include a reference terminal or a terminalconnected with a signal electrode (such as a gate electrode) formed onthe surfaces of the semiconductor chips 11, 12. The control terminals 70are electrically connected to the semiconductor chips 11, 12 by bondingwires or the like (not shown).

The electrode terminals for main current 60 are projected from one sideof the semiconductor module 1 a, and the control terminals 70 arearranged on the opposite side of the semiconductor module 1 a. In otherwords, the main current electrode terminals 60 and the control terminals70 are arranged in two opposite directions on both sides of thesemiconductor module 1 a.

Further, semiconductor module 1 a according to this embodiment is sealedor molded by the molded resin 50 a, which is a seal member, in such amanner as to expose the heat radiation surfaces 21, 31 of the heat sinks20, 30. Specifically, as shown in FIG. 1B, the molded resin 50 is filledin the gap between the pair of the heat sinks 20, 30 and around thesemiconductor chips 11, 12.

Ordinary molding material such as epoxy resin can be used for the moldedresin 50. The heat sinks 20, 30 can be easily molded with the moldedresin 50 a by such a method as a potting or a transfer molding using amolding die.

As described above, the semiconductor device 100 according to thisembodiment basically comprises the semiconductor module 1 a includingthe semiconductor chips 11, 12 as semiconductor elements, the heat sinks20, 30 as metal plates thermally connected to the semiconductor chips11, 12 to transfer heat from the semiconductor chips 11, 12 and themolded resin 50 as a seal member to hermetically seal the semiconductorchips 11, 12 and the heat sinks 20, 30 in such a manner as to expose theheat radiation surfaces 21, 31 of the heat sinks 20, 30.

Further, in the semiconductor device 100 according to this embodiment,the heat radiation surfaces 21, 31 of the heat sinks 20, 30 of thesemiconductor module 1 a are cooled by a refrigerant. The refrigerant isa fluid such as air, water or oil. Specifically, the refrigerant is thecooling water or the oil for automobiles on which the semiconductordevice 100 is mounted.

The cooling structure described above is unique to this embodiment, inwhich as shown in FIGS. 1A, 1B, a part of the molded resin 50 a, whichis a seal member, of the semiconductor module 1 a is used as therefrigerant path 53.

Specifically, as shown in FIGS. 1A and 1B, the molded resin 50 aincludes a sealing part 51 a for sealing the semiconductor chips 11, 12and the heat sinks 20, 30, and a wall part 52 a arranged around thesealing part 51 a and having open ends 55 a projected more than the heatradiation surfaces 21, 31 of the heat sinks 20, 30. In this embodiment,the wall part 52 a are arranged in annular form surrounding the heatradiation surfaces 21, 31.

In the semiconductor device 100 according to this embodiment, openings53 a are formed between the heat sinks 20, 30 of the sealing part 51 andthe wall part 52, and the openings 53 a are used as a refrigerant path.

The configuration of the molded resin 50 a can be easily realized with adie molding or the like process. Also, in the molded resin 50 a, thesealing part 51 a and the wall part 52 a may be separated. After formingthe sealing part 51, for example, the wall part 52 a may be formedintegrally with the sealing part 51 a by bonding or the like.

Next, a method of fabricating the semiconductor device 100 having theabove-mentioned configuration will be explained briefly with referenceto FIGS. 1A and 1B.

First, the first and second semiconductor chips 11, 12 are soldered onthe upper surface of the lower heat sink 20. In this case, the first andsecond semiconductor chips 11, 12 are stacked on the upper surface ofthe lower heat sink 20 each through, for example, a Sn solder foil.

After that, the assembly is heated to beyond the melting point of thesolder by a heater (reflow soldering). In this way, the solder foil,after being melted, is cooled and hardened. Then, the control terminals70 are connected with the semiconductor chips 11, 12 by wire bonding asrequired.

Then, the upper heat sink 30 is soldered on the first and secondsemiconductor chips 11, 12. In the process, the upper heat sink 30 isplaced on the semiconductor chips 11, 12 each through a solder foil, andthe solder foil is melted and hardened by a heater.

Each melted solder foil, after being hardened in this way, becomes thefirst solder 41 and the second solder 42 described above. Throughsolders 41, 42, the lower heat sink 20, the first and secondsemiconductor chips 11, 12 and the upper heat sink 30 can bemechanically, electrically and thermally connected to each other.

As described above, a conductive adhesive can be used in place of thesolder 41, 42. In such a case, the joining process is executed using theconductive adhesive instead of the solder.

After that, the molded resin 50 a is filled in the gap and on the outerperiphery of the heat sinks 20, 30 by the transfer molding or potting.At the same time, the openings 53 a are formed as a refrigerant path.

As a result, as shown in FIGS. 1A and 1B, the molded resin 50 a isfilled in the gap and on the outer periphery of the heat sinks 20, 30thereby to seal the semiconductor chips 11, 12 and the heat sinks 20,30, while at the same time forming the openings 53 a as a refrigerantpath. In this way, the semiconductor device 100 comprising thesemiconductor module 1 a, is completed.

According to this embodiment, there is provided a semiconductor device100 comprising the semiconductor module 1 a including the semiconductorchips 11, 12 as semiconductor elements, the heat sinks 20, 30 as metalplates thermally connected with the semiconductor chips 11, 12 fortransmitting heat from the semiconductor chips 11, 12, and the moldedresin 50 a as a seal member for covering and sealing the semiconductorchips 11, 12 and the heat sinks 20, 30 in such a manner as to expose theheat radiation surfaces 21, 31 of the heat sinks 20, 30, wherein theheat radiation surfaces 21, 31 are cooled by the refrigerant and whereina part of the molded resin 50 a is formed as a refrigerant path 53.

A part of the molded resin 50 a of the semiconductor module 1 isconfigured as the refrigerant paths 53 through which the refrigerantflows, and therefore such independent members as a cooling tube and acase are not required, unlike in the prior art, thereby decreasing thesize of the device.

Thus, according to this embodiment, there is provided a compact, simplecooling structure of a semiconductor device 100 comprising thesemiconductor module 1 including the semiconductor chips 11, 12connected with the heat radiating heat sinks 20, 30 and sealed with themolded resin 50, wherein the heat radiation surfaces 21, 31 of the heatsinks 20, 30 are cooled by the refrigerant.

Specifically, according to the prior art, cooling tubes, cooling fins ora case to form a refrigerant path are arranged on the outside of thesemiconductor module, which has a package to seal the semiconductor by aseal member of resin or the like, thereby increasing the size of thedevice. The size of the semiconductor device 100 according to thisembodiment, on the other hand, can be maintained substantially withinthe outline of the seal member, i.e. the size of the semiconductorpackage.

Also, according to this embodiment, the molded resin 50 a includes thesealing part 51 a for sealing the semiconductor chips 11, 12 and theheat sinks 20, 30, and the wall part 52 a surrounding the sealing part51 a and having opening ends projected more than the heat radiationsurfaces 21, 31 of the heat sinks 20, 30, wherein the openings 53 a ofthe sealing part 51 a is formed as the refrigerant path between themetal plate 20, 30 and the wall part 52 a.

Further, one of the features of this embodiment lies in that the wallpart 52 a is arranged in annular form to surround the side of the heatsinks 20, 30. According to this embodiment, the molded resin 50 a havingthe wall part 52 a can properly realize the openings 53 as a refrigerantpath.

According to this embodiment, the molded resin 50 a is used as the sealmember. Nevertheless, any electrically insulating material other thanresin, such as a ceramic, can be adopted to seal the elements.

Further, as another feature of this embodiment, as shown in FIG. 1A, theelectrode terminals for main current 60 are projected from one side ofthe semiconductor module 1 a, and the control terminals 70 are arrangedon the opposite side of the semiconductor module 1 a.

As described above, with the semiconductor device 100 according to thisembodiment, the absence of the case or the like makes it possible toproject the electrode terminals 60 and the control terminals 70 from theopposite sides of the semiconductor module 1 a.

The conventional semiconductor device has unavoidably increased in size,because the terminals had to be led out only in one direction from thesemiconductor module, and the insulation distance of the wires connectedto the terminals had to be secured in the same space.

According to this embodiment, in contrast, the two types of terminals60, 70 can be arranged in two opposite directions, and therefore thesize of the semiconductor device 100 can be advantageously reduced.

FIG. 2 is an enlarged sectional view showing the neighborhood of theheat radiation surfaces 21, 31 of the heat sinks 20, 30 of thesemiconductor device 100 according to a modification of the firstembodiment.

As shown in FIG. 2, electrical insulating layers 21 a, 31 a are formedon the surfaces of the heat sinks 20, 30 exposed from the moldingcompound 50. The surfaces 21 a, 31 a are used as heat radiation surfaces21, 31.

In FIG. 2, the insulating layers 21 a, 31 a are shown in the same part.Actually, however, the insulating layer 21 a is of course arranged onthe surface of the lower heat sink 20, and the insulating layer 31 a onthe surface of the upper heat sink 30.

This configuration electrically insulates the heat radiation surfaces21, 31 of the heat sinks 20, 30 from the refrigerant. As a result, evenif the refrigerant is an electrically conductive material such as water,the circuits of the semiconductor chips 11, 12 cannot be adverselyaffected.

The insulating layers 21 a, 31 a may be made of a resin of a high heatconductivity such as polyamide mixed with alumina or glass filler, or aceramic substrate metallized or brazed with a metal foil and soldered tothe heat sinks 20, 30.

If the refrigerant is an electrical insulating material such as air oroil, the heat radiation surfaces 21, 31 of the heat sinks 20, 30 may notbe electrically insulated from the semiconductor chips 11, 12. In such acase, the insulating layers 21 a, 31 a are not formed, and the surfacesof the heat sinks 20, 30 serve as the heat radiation surfaces 21, 31.

FIGS. 1A and 1B show only one semiconductor module la. According to thisembodiment, however, the semiconductor device may include a plurality ofconnected semiconductor modules.

FIGS. 3A, 3B are diagrams showing an example of the semiconductor deviceaccording to this embodiment comprising a plurality of the connectedsemiconductor modules 1 having the respective refrigerant paths 53 acommunicating with each other. FIG. 3A is an exploded perspective viewof the semiconductor device, and FIG. 3B a sectional view of thesemiconductor device taken in one-dot chain line B-B in FIG. 3A.

In the semiconductor device shown in FIGS. 3A and 3B, a plurality of(three pieces in the shown case) semiconductor modules 1 are stacked andconnected in sequence with the refrigerant paths thereof as the openings53 a communicating with each other.

The first semiconductor module 1 a in the stack structure has a coverplate 80 a having a refrigerant inlet 81 a and a refrigerant outlet 81b. The inlet 81 a and the outlet 81 b communicate with the openings 53.

The last semiconductor module 1 a of the stack, on the other hand, has acover plate 80 b having no inlet or outlet, whereby the open end of thelast semiconductor module 1 a are closed. In this way, the inlet 81 a,the outlet 81 b and the openings 53 are connected to each other, so thatthe refrigerant entering the inlet 81 a flows out of the outlet 81 bthrough the openings 53 to come into contact with the metal plates 20,30.

The cover plate 80 a having the inlet 81 a and the outlet 81 b and thecover plate 80 b no inlet and outlet can be fabricated by forming orpressing a material such as resin, metal or ceramics.

In the plurality of the stacked semiconductor modules 1, the heatradiation surfaces 21, 31 thereof are arranged in opposed relation toeach other, and the refrigerant flows through the refrigerant pathbetween the opposed heat radiation surfaces 21, 31.

The semiconductor modules 1 a are connected to the adjoiningsemiconductor modules 1 a at the ends of each wall part 52 a and thefirst and the last of the semiconductor modules 1 a are respectivelyconnected to the cover plates 80 a, 80 b at the other end of the wallpart 52 a. The ends of the wall parts 52 a is bonded by using anadhesive 82.

Further, as shown in FIG. 3B, the end surfaces of each wall part 52 a,which is used to connect the modules or cover plates, has preferably aconcave or a convex portion for the positioning purpose. In FIG. 3B, theend surfaces of each wall part 52 a has a convex portion 54 a or acorresponding concave portion, respectively. The convex portion of thewall part 52 a is adapted to engage the concave portion of the adjoiningwall part 52.

In the semiconductor device shown in FIGS. 3A, 3B, a plurality of thesemiconductor modules 1 are stacked, and openings 53 a formed in themolded resin 50 a of each semiconductor module 1 a serve as a part ofthe refrigerant path. Simply by connecting the individual semiconductormodules 1 a, therefore, the refrigerant path can be configured.

In forming the refrigerant path, the pressure mechanism and additionalcooling members are not required unlike in the prior art, and thereforethe cooling structure according to the embodiment can be easilyrealized. As a result, the device is reduced in size and simplified,thereby making it possible to simplify the assembly work.

As each semiconductor module 1 a is formed by molding resin, a very highouter dimensional accuracy (e.g. ±0.1 mm or less) as compared with theprior art can be easily achieved.

Even in the case where a multiplicity of the semiconductor modules 1 areconnected, therefore, the positional accuracy of the terminals, i.e. themain current electrode terminals 60 and the control terminals 70 of thestacked semiconductor modules 1 can be improved over the prior art,which advantageously facilitate the positioning of the terminals of thesemiconductor device when mounted on an external circuit board.

In the semiconductor device shown in FIGS. 3A, 3B, the end surfaces ofthe wall parts 52 to be connected have a convex portion or a concaveportion corresponding to the convex portion for the positioning purpose,and therefore the interconnection of the wall parts 52 is facilitated.

(Second Embodiment)

According to the second embodiment of the invention, the heat radiationsurfaces 21, 31 of the heat sinks 20, 30 are formed with fins or thelike to improve the heat radiation performance.

FIG. 4 is a perspective view schematically showing a configuration of asemiconductor device 200 according to the second embodiment of theinvention. FIG. 5A is a diagram showing an example of the sectionalconfiguration along a one-dot chain line C-C in FIG. 4, and FIG. 5B adiagram showing another example of the sectional configuration along aone-dot chain line C-C in FIG. 4.

In the semiconductor device according to the first embodiment, heat isradiated from the heat radiation surfaces 21, 31 of the heat sinks 20,30 made of metal. To improve the heat radiation performance, therefore,the heat radiation surfaces 21, 31 preferably have rough surfaces.

The rough heat radiation surfaces 21, 31 are formed by being roughenedor grooved by etching or machining.

Also, to improve the heat radiation from the heat radiation surfaces 21,31 of the heat sinks 20, 30, as shown in FIGS. 4, fins 83 projectingfrom the heat radiation surfaces 21, 31 of the heat sinks 20, 30 arepreferably formed.

The fins 83 are made, for example, of cooper or alminium. The fins 83can be formed with the heat sinks 20, 30 by integral molding in pressworking. Alternately, the fins 83 can be separately made and joined tothe heat sinks 20, 30.

The semiconductor device 200 shown in FIGS. 4, 5A, 5B is also configuredof a plurality of semiconductor modules 1 connected to each other. Theconnection structure and the operational effect are basically similar tothose of the semiconductor device shown in FIGS. 3A, 3B.

Specifically, also in the semiconductor device 200 having a plurality ofthe stacked semiconductor modules 1 as shown in FIGS. 4, 5A, 5Baccording to this embodiment, the refrigerant path can be configuredsimply by connecting the individual semiconductor modules 1 a. Thus thecooling structure can be easily realized, with the result that thedevice can be reduced and simplified thereby making it possible tosimplify the assembly work.

Also in the semiconductor device 200, the terminal position accuracy isimproved over the prior art in spite of the fact a multiplicity of thesemiconductor modules 1 are connected. Thus, the positioning of theterminals is facilitated in mounting the semiconductor device on thecircuit board.

Further, in the semiconductor device 200 according to this embodiment,as shown in FIGS. 4, 5A, 5B, the heat radiation surfaces 21, 31 of theplurality of the stacked semiconductor modules 1 are arranged in opposedrelation to each other, and the fins 83, 83 a, 83 b are arranged on thesurfaces of the heat radiation surfaces 21, 31.

In this case, as shown in FIG. 4, hf is the height of each fin 83, and Dis the height of each wall part 52 from the heat radiation surfaces 21,31.

In the example shown in FIG. 5A, the wall part 52 are projected morethan the fins 83 a. Specifically, the fin height hf and the wall partheight D have the relation hf<D, and therefore, the fins 83 a arrangedon the heat radiation surfaces 21, 31 in opposed relation to each otherdo not advantageously interfere with each other.

In the example shown in FIG. 5B, on the other hand, the fins 83 b areprojected more and taller than the wall part 52 a. In other words, thefin height hf and the wall part height D hold the relation hf>D.

On the heat radiation surfaces 21, 31 in opposed relation to each other,the fins 83 b on one of the heat radiation surfaces are displaced fromthe fins 83 b on the other heat radiation surface. Therefore, the fins83 b formed on the heat radiation surfaces 21, 31 in opposed relation toeach other do not advantageously interfere with each other.

On the heat radiation surfaces 21, 31 in opposed relation to each other,the fins 83 on one of the heat radiation surfaces and the fins 83 on theother heat radiation surface are preferably displaced from each otheralso in the case where the fin height hf and the wall part height D holdthe relation hf=D. By doing so, the fins 83 can be advantageouslyprevented from interfering with each other.

In the example shown in FIGS. 4, 5A, 5B, the fins 83, 83 a, 83 b havethe form similar to the teeth of a comb projected from the surfaces ofthe heat radiation surfaces 21, 31 of the heat sinks 20, 30.

In the case where the fin height hf and the wall part height D hold therelation hf≥D, therefore, the fins 83 b on the heat radiation surfaces21, 31 in opposed relation to each other are arranged in such a manneras to engage each other.

The roughness on the heat radiation surfaces 21, 31 of the heat sinks20, 30 and the fins 83 projected from the heat radiation surfaces 21, 31can of course be formed also in the semiconductor device having only onesemiconductor module 1 to improve the heat radiation performance.

FIGS. 5A, 5B show that one end of each main current electrode terminal60 formed integrally with the upper heat sink 30 is projected out of themolded resin 50 a.

Also, FIGS. 5A, 5B show that the control terminals 70 for thesemiconductor chips 11, 12 are projected out of the molded resin 50 aand electrically connected to the semiconductor chips 11 through thebonding wires 71.

Also in this embodiment, the various modifications described in theforegoing embodiments are applicable as far as possible.

(Third Embodiment)

According to the third embodiment of the invention, a position of theopenings formed as a refrigerant path in the molded resin is differentfrom that of the opening in the first and second embodiments. FIGS. 6A,6B are schematic diagrams showing a semiconductor device 300 accordingto the third embodiment of the invention. FIG. 6A is a perspective view,and FIG. 6B a side view as taken in the direction of arrow A′.

In the first and second embodiments, the refrigerant path 53 is formedas openings 53 between the sealing part 51 and the wall part 52 of themolded resin 50

In the semiconductor device 300 according to this embodiment, incontrast, as shown in FIGS. 6A, 6B, the molded resin 50 b includes thesealing part 51 b and the wall part 52 b, and the refrigerant path isformed as the openings 53 b on the wall part 52 b. This openings 53 b isindicated as an area hatched for convenience sake in FIG. 6B.

Also according to this embodiment, the semiconductor device 300comprises the semiconductor module 1 b including the semiconductor chips11, 12 as the semiconductor elements, the heat sinks 20, 30 as the metalplates and the molded resin 50 as the sealing part, wherein the heatradiation surfaces 21, 31 of the heat sinks 20, 30 of the semiconductormodule 1 b are cooled by the refrigerant, and wherein a part of themolded resin 50 b forms the refrigerant path 53 in which the refrigerantflows.

Also, in the semiconductor device 300 according to this embodiment, itis not necessary to use the cooling tube and the additional members usedin the prior art, and therefore the size of the device is not beincreased, resulting in a compact, simple cooling structure.

Further, the semiconductor device according to this embodiment maycomprise either a single or a plurality of semiconductor modules 1 bconnected in sequence.

FIGS. 7A, 7B show an example of the semiconductor device according tothis embodiment, in which a plurality of the semiconductor modules 1 arestacked and connected in sequence, and the respective refrigerant paths53 communicate with each other. FIG. 7A is a perspective view of thesemiconductor device, and FIG. 7B a sectional view taken in one-dotchain line D-D in FIG. 7A.

In the semiconductor device shown in FIGS. 7A, 7B, a plurality of (2×3in the shown case) semiconductor modules 1 b are stacked and connectedin sequence, and the openings 53 b formed as the respective refrigerantpaths communicate with each other.

Also, this stack structure is connected to a cover plate 80 c having arefrigerant inlet 81 c, a cover plate 80 e having a refrigerant outlet81 e and cover plates 80 d, 80 f having no inlet and outlet, wherein theinlet 81 c, the outlet 81 e and the openings 53 communicate with eachother. In this way, the inlet 81 c, the outlet 81 e and the openings 53b are connected to each other, so that the refrigerant entering theinlet 81 c exits from the outlet 81 e through the openings 53 b.

An example of assembling the semiconductor device having sixsemiconductor modules 1 shown in FIGS. 7A and 7B is as following. First,a pair of two semiconductor modules 1 b is formed by bonding the endsurfaces 55 b of the wall parts 52 b of the two semiconductor modules 1.Next, three pieces of the pair of two semiconductor modules 1 areconnected in sequence by bonding the side surfaces 55 b of the wallparts 52 b of the pair. Finally, the semiconductor device is formed bycovering four sides having no terminals of the connected semiconductormodules with the cover plates 80 c-80 f. If the semiconductor device hasonly three semiconductor modules, the three semiconductor modules areconnected in sequence by bonding the side surfaces 55 b of the wallparts 52 b of the three semiconductor modules. It is noted that thesemiconductor device in FIGS. 7A and 7B can be alternatively formed bybonding a pair of the three semiconductor modules at the end surfaces 55b of the wall parts 52 b.

Further, according to this embodiment, the surfaces of the wall parts 52to connect the modules and the covers, i.e. the side and end surfaces ofthe wall parts 52 may have a convex or a concave portion for thepositioning as shown in FIGS. 3A, 3B.

As described above, also in this embodiment, the semiconductor device isconfigured of a plurality of the semiconductor modules 1 stacked andconnected to each other, while the respective refrigerant paths 53communicate with each other. With this semiconductor device, the size isreduced, and the structure and the assembly work are simplified, so thateven in the case where a multiplicity of the semiconductor modules 1 areconnected, the terminal position accuracy is improved over the priorart.

FIG. 8 is a perspective view showing a semiconductor device as amodification of the third embodiment.

As shown in FIG. 8, the heat sinks 20, 30 are modified to the shape ofthe wall part 52 b, and the exposure area of the heat sinks 20, 30 isincreased. Thus, the area of the heat sinks 20, 30 to be in contact withthe refrigerant increases for an improved heat radiation performance.

The semiconductor device according to this embodiment may also compriseeither a single semiconductor module 1 b or connected semiconductormodules 1 b.

The semiconductor device according to this embodiment can also becombined with any of the embodiments or modifications thereof describedabove, as far as possible.

Also in this embodiment, for example, the insulating layers 21A, 31A(FIG. 2) may be formed as the heat radiation surfaces 21, 31 of the heatsinks 20, 30, the heat radiation surfaces 21, 31 may be roughened, orthe fins 83 (FIGS. 4, 5A, 5B) may be arranged on the heat radiationsurfaces 21, 31.

(Fourth Embodiment)

A fourth embodiment of the invention is intended to improve corrosionresistance to the refrigerant flowing in the refrigerant path. FIG. 9 isa diagram showing a schematic sectional configuration of a semiconductordevice 400 according to the fourth embodiment of the invention.

As shown in FIG. 9, in the semiconductor device 400 according to thisembodiment, films 84 having a corrosion resistance to the refrigerantare formed on the inner wall surfaces of the openings 53 which arerefrigerant paths. The films 84 are made of, for example, ceramic, glassor parylene.

The semiconductor device 400 according to this embodiment comprises thesemiconductor module la including the semiconductor chips 11, 12, theheat sinks 20, 30 as metal plates and the molded resin 50 as a sealmember, wherein the heat radiation surfaces 21, 31 of the heat sinks 20,30 of the semiconductor module 1 a are cooled by the refrigerant, andwherein the films 84 having the corrosion resistance to the refrigerantare formed on the inner wall surfaces of the refrigerant paths 53.

With the semiconductor device 400 according to this embodiment, unlikein the prior art, the additional members such as the cooling tube andthe case are not required, thus not increasing the size. As a result, acompact, simple cooling structure is realized, and the corrosionresistance to the refrigerant is improved.

Roughening the heat radiation surface, forming fins on the heatradiation surfaces, and stacking the semiconductor modules 1 a can bearbitrarily applied to the semiconductor device 400 according to thisembodiment. In this way, this embodiment can be combined with any of theaforementioned embodiments or modifications thereof appropriately as faras possible.

(Fifth Embodiment)

The fifth embodiment of the invention is realized by using a differentmethod of stacking the semiconductor modules 1 c. In other words, thesemiconductor modules 1 c are stacked at an angle, i.e. tilted. Thesemiconductor device 500 according to this embodiment has at least onesemiconductor module 1 c.

FIGS. 10a, 10b are schematic diagrams showing the semiconductor device500 having the semiconductor module 1c according to the fifth embodimentof the invention. FIG. 10A is a perspective view, and FIG. 10B asectional view taken in one-dot chain line E-E in FIG. 10A.

As shown in FIGS. 10A, 10B, in the semiconductor device 500 according tothis embodiment, a portion of the wall part 52 c of the molded resin 50c is formed shorter than the opposite portion of the wall part 52 c.

The semiconductor device 500 as shown in FIGS. 10A, 10B, is formed bymodifying the semiconductor 300 shown in FIGS. 6A, 6B. According to thesemiconductor device 500, the lower wall part 52 c-2 is formed shorterthan the upper wall part 52 c-1. As a result, as shown in FIG. 10B, thecross section of the semiconductor device 500 has a sectorial shape.

Also in the semiconductor device 500 according to this embodiment, apart of the molded resin 50 c is configured as a refrigerant path 53 inwhich the refrigerant flows, thereby realizing a compact, simple coolingstructure.

Further, according to this embodiment, the advantage of the sectorialsection of the semiconductor device 500 becomes remarkable in the casewhere a plurality of the semiconductor modules 1 c are connected. FIG.11 is a sectional view schematically showing the configuration of thesemiconductor device according to this embodiment in which a pluralityof the semiconductor modules 1 are connected with the respectiverefrigerant paths 53 communicating with each other.

As shown in FIG. 11, according to this embodiment, there is provided asemiconductor device comprising stacked and connected semiconductormodules 1 c, which are connected in a sectorial form.

The sectorial connection of the plurality of the semiconductor modules 1c includes a case in which additional semiconductor modules 1 c areconnected into an annular or polygonal form.

In the case where the semiconductor device according to this embodimentis used as an inverter for the motor or the like, the similarity inshape of the semiconductor device to a rotary machine such as a motorcan shorten the wiring distance and simplifies the connection, therebyeffectively reducing noises.

The semiconductor device 500 shown in FIGS. 10A, 10B has the refrigerantpaths i.e. openings 53 of the wall part 52 c. However, the refrigerantpaths according to the present embodiment may be configured as openings53 of the sealing part 51 between the heat sink 20, 30 and the wall part52.

Specifically, the semiconductor device shown in FIG. 1 can also beformed to have a sectorial section unique to this embodiment bydifferentiating the height of the upper and lower portion of the wallparts 52 as shown in FIGS. 10A, 10B.

The semiconductor device according to this embodiment can also becombined appropriately with any of the aforementioned embodiments ormodifications thereof.

(Sixth Embodiment)

According to a sixth embodiment of the invention, there is provided asemiconductor device in which a plurality of semiconductor modules 1 arestacked to make a power circuit.

FIG. 12 is a sectional view schematically showing a generalconfiguration of a power converter 600 as a semiconductor deviceaccording to the sixth embodiment of the invention. The power converter600 shown in FIG. 12 represents an example using the semiconductormodule 1 according to the first embodiment described above.

The power converter 600 is a power circuit which is formed by stacking aplurality of the semiconductor modules 1 a, capacitors 85, 86 and areactor 87, which are also heat generating elements. The resultingassembly is electrically connected with a first bus bar 91, a second busbar 92 and a third bus bar 93.

The first bus bar 91 and the second bus bar 92 are input bus bars forthe input connection of the power circuit, and the third bus bar 93 isan output bus bar for the output connection.

The first capacitor 85, the second capacitor 86 and the reactor 87,which are the heat generating parts, like the semiconductor module 1 a,are sealed with the molded resin 50 d, being a seal member, which hasopenings 53 d as a refrigerant path.

The semiconductor modules 1 a, the capacitors 85, 86 and the reactor 87are stacked as shown in FIG. 12. At the ends of the stack structure, acover plate 80 a having an inlet 81 a and an outlet 81 b and a coverplate 80 b having no inlet and outlet are arranged, and each bonded byusing an adhesive 82.

In the power converter 600, refrigerant paths are formed by the openings53 communicating with each other, and the refrigerant flows from theinlet 81 a through the refrigerant path to outlet 81 b, thereby coolingthe capacitors 85, 86 and the reactor 87 as well as the semiconductormodules 1.

The circuit configuration of the power converter 600 is shown in FIG.13. A plurality of the semiconductor modules 1 and the second capacitor86 make up a converter 102, while the semiconductor module 1, the firstcapacitor 85 and the reactor 87 make up an inverter 101.

As described above, this embodiment provides the power converter 600 asa semiconductor device comprising a plurality of the semiconductormodules 1 a, which are stacked and connected, with the respectiverefrigerant paths 53 communicating with each other, wherein the stackedsemiconductor modules 1 is configured as a power circuit.

As a result, the power converter 600 according to this embodimentexhibits the same advantageous effects as the semiconductor devicehaving the plurality of the semiconductor modules 1 a connected asdescribed above.

Further, as a feature of this embodiment, the heat generating elements85, 86, 87 are stacked with the semiconductor modules 1, and cooled bythe refrigerant.

Also, as shown in FIG. 12, further, a feature of the power conversioncircuit 600 according to this embodiment is that the first bus bar 91and the second bus bar 92, which are the input wirings of the powercircuit, are arranged in proximity and parallel to each other. Thedevice size can be reduced by using this bus bar arrangement.

FIGS. 14A, 14B, 14C are diagrams showing a detailed wiring configurationof the bus bars of the semiconductor module 1 in the power converter600. FIG. 14A is a front view, FIG. 14B a top plan view of thesemiconductor module, and FIG. 14C a diagram showing an equivalentcircuit of the wiring configuration. In FIG. 14B, the sectional view ofthe configuration of the molded resin 50 of the semiconductor module 1 ais shown.

As shown in FIG. 14A the first bus bar 91 and the second bus bar 92,which are the input bus bars, are connected by screws or welding to theelectrode terminal 60 of the semiconductor module 1 a, which is formedas an input terminal of the power converter 600, and the third bus bar93, which is the output bus bar, is connected by screws or welding tothe electrode terminal 60 of the semiconductor module 1, which is formedas an output terminal.

The control terminals 70 of the semiconductor module 1 are electricallyconnected to the control circuit board 110. The control terminals 70 areinserted into the openings formed in a control circuit board 110 andbonded to the circuit board 110 by soldering.

In this case, as shown in FIG. 14C, two power circuits are included ineach semiconductor module 1. As an alternative, as shown in FIGS. 15A,15B, 15C, a circuit configuration equivalent to the circuit shown inFIG. 14A, 14B, 14C may be realized using two semiconductor modules 1.

FIGS. 15A, 15B, 15C are diagrams showing another example of the wiringconfiguration of the bus bars of the semiconductor modules 1 in thepower converter 600. FIG. 15A is a front view, FIG. 15B a top plan viewof the semiconductor module, and FIG. 15C a diagram showing anequivalent circuit of the wiring configuration. FIG. 15B also shows asectional configuration of the molded resin 50 a of the semiconductormodules 1 a.

In the example shown in FIG. 15A, input bus bars 91, 92 are connected byscrews or welding to the main current electrode terminal 60, which isformed as an input terminal, and an output bus bar 93 is connected byscrews or welding to the main current electrode terminal 60, which isformed as an output terminal. Also, the control terminals 70 areelectrically connected to the control circuit board 110.

Thus, the configuration shown in FIGS. 15A, 15B, 15C is an example inwhich the two stacked semiconductor modules 1 are connected electricallyto each other by the bus bars 91 to 93, thereby realizing the circuitconfiguration equivalent to the circuit shown in FIGS. 14A, 14B, 14C.This configuration is applicable to the power converter 600 in FIG. 12.

FIGS. 16, 17 are diagrams showing first and second modifications of thisembodiment.

In the first modification shown in FIG. 16, an electrically insulatingmember 94 of such a material as resin or ceramic is interposed betweenthe first bus bar 91 and the second bus bar 92 arranged in proximity andparallel to each other.

In the second modification shown in FIG. 17, on the other hand, thefirst bus bar 91 and the second bus bar 92 arranged in proximity andparallel to each other are contained and sealed by the electricallyinsulating member 95 of such a material as resin or ceramics.

The configuration using the insulating member 94, 95 secures theelectrical insulation between the first bus bar 91 and the second busbar 92 arranged in proximity and parallel to each other, and thereforecan reduce the interval between the first bus bar 91 and the second busbar 92 being as the input bus bars, thereby advantageously making itpossible to reduce the size and the parasitic inductance of the wiring.

Also with the semiconductor device according to this embodiment, any ofthe embodiments described above and the modifications thereof can beappropriately combined as far as possible.

(Other Embodiments)

According to each of the embodiments described above, stackedsemiconductor modules 1 are connected to form a semiconductor device,using the adhesives 82. The semiconductor modules 1, however, are notnecessarily connected by bonding but may be connected by other means.

In the semiconductor device shown in FIGS. 3A and 3B, for example,O-rings 82 a may be used in place of the adhesives 82 (see FIG. 3B).

When the O-rings 82 a are used, the stacked semiconductor modules 1 heldby the cover plates 80 a, 80 b are connected to each other by pressingthe stacked modules by the cover plates 80 a, 80 b arranged at the endsof the stacked modules. The cover plates 80 can be fixed to each otherby fastening means, for example, screws (not shown).

In such a case, with the semiconductor device shown in FIGS. 3A and 3B,each adjoining semiconductor modules 1 a are kept in contact with eachother through the O-ring 82 a so that the contact portion of thesemiconductor modules 1 are sealed by the O-ring 82 a.

By doing so, the refrigerant paths i.e. openings 53 are formed underpressure through the O-rings 82 a, and therefore the replacement orrepair work is facilitated if the stacked semiconductor modules 1include a defective element. The connection structure using the O-ringscan be employed as far as possible in the embodiments described above.

In the case where the semiconductor device is configured of a pluralityof the semiconductor modules 1 connected with each other in theaforementioned embodiments, a visible surface of the stack structure ofthe plurality of the semiconductor modules 1 desirably is used as theprinting surfaces of the semiconductor modules 1.

In the semiconductor device, for example, shown in FIGS. 3A and 3B, theouter side surface of the wall part 52 a of the molded resin 50 a ofeach semiconductor module 1 a included in the stack structure forms avisible surface, i.e. a printing surface.

When characters or numerals are printed on the printing surface of thestacked semiconductor modules 1 a, the printing surface can be visuallychecked and therefore the serial numbers, etc. of the semiconductormodules 1 a can be advantageously confirmed from the viewpoint ofmaintenance, for example.

According to the embodiments described above, the heat sinks 20, 30,which are metal plates, are arranged on the two sides of thesemiconductor elements 11, 12, respectively, and the heat radiationsurfaces 21, 31 of the heat sinks 20, 30 are both exposed from themolded resin 50 a. As an alternative, the heat radiation surface of onlyone of the heat sinks 20, 30 may be exposed from the molded resin 50 a.

Further, the heat sink may alternatively be arranged only one side ofthe semiconductor elements 11, 12, and the heat radiation surface of theparticular heat sink may be exposed from the molded resin 50 a. In thesemiconductor device 100, for example, shown in FIGS. 1A and, 1B, thelower heat sink 20 may be omitted and the upper heat sink 30 may be onlyused. Alternatively, only the lower heat sink 20 may be used without theupper heat sink 30.

Specifically, the heat sinks 20, 30, which are the metal plates of thesemiconductor module 1, are arranged at least on one surface of thesemiconductor chips 11, 12 as semiconductor elements, and only thesurfaces of the heat sinks 20, 30 formed on the one surface of thesemiconductor chips 11, 12 may be exposed from the molded resin 50 a,which is a seal member.

Also, in FIGS. 1A and 1B, the two large openings 53 are formed as therefrigerant path of the sealing part 51 a between the metal plates 20,30 and the wall part 52 a. However, at least one of the openings can bereplaced with a plurality of openings or through holes.

The semiconductor module 1 b of FIGS. 6A and 6B has the refrigerant pathformed with the openings 53 in the wall part 52 as a notch cut from apart of the wall part 52. However, the openings formed in the wall part52 may of course leave the outer frame to form an opening or a pluralityof openings.

In short, this invention provides a semiconductor device comprising, asessential parts, semiconductor elements, metal plates thermallyconnected with the semiconductor elements for transmitting heat from thesemiconductor elements, and a seal member for containing and sealing thesemiconductor elements and the metal plates in such a manner as toexpose the heat radiation surfaces of the metal plate, wherein the heatradiation surfaces are cooled by the refrigerant, and wherein a part ofthe seal member is formed as a refrigerant path in which the refrigerantflows. The other component parts can be appropriately designed.

What is claimed is:
 1. A semiconductor device comprising: asemiconductor element; a heat sink made of metal thermally connected tothe semiconductor element; and a resin for completely covering thesemiconductor element and the heat sink as one body in such a manner asto expose a heat radiation surface of the heat sink, the resin adheringto the semiconductor element and the heat sink without space; wherein apart of the resin offsetting externally from the resin is used as a partof an outer wall surface of a refrigerant path in which a refrigerantflows, the refrigerant cooling the heat radiation surface, therefrigerant path is an open area through which the refrigerant flows,the wall surface of the refrigerant path directly faces the open areathrough which the refrigerant flows, and the refrigerant flows on theexposed radiation surface of the heat sink.
 2. The semiconductor deviceaccording to claim 1, wherein the heat radiation surface is a metal. 3.The semiconductor device according to claim 1, wherein the heatradiation surface is a metal coated with an insulator.
 4. Thesemiconductor device according to claim 2, wherein the heat radiationsurface of the metal is rough.
 5. The semiconductor device according toclaim 2, wherein the heat radiation surface of the metal has at leastone fin projecting from the same surface.
 6. The semiconductor deviceaccording to claim 3, wherein the heat radiation surface is formed asthe surface of the insulating layer on the surface of the metal.
 7. Thesemiconductor device according to claim 1, wherein an inner wall surfaceof the refrigerant path is covered with a film having corrosionresistance against the refrigerant.
 8. The semiconductor deviceaccording to claim 1, wherein electrode terminals for main current areprojected from one side of the resin, and wherein control terminals arearranged on the opposite side of the resin.
 9. The semiconductor devicecomprising: a plurality of semiconductor modules, each of thesemiconductor modules according to claim 1, wherein the semiconductormodules are stacked and connected so that the refrigerant paths of thesemiconductor modules are communicated with each other.
 10. Thesemiconductor device according to claim 9, wherein the heat radiationsurface is a metal.
 11. The semiconductor device according to claim 9,wherein the heat radiation surface is a metal coated with an insulator.12. The semiconductor device according to claim 9, wherein the heatradiation surfaces of the stacked semiconductor modules are placedopposite with each other.
 13. The semiconductor device according toclaim 9, wherein the semiconductor modules are connected at end or sidesurfaces of the wall parts.
 14. The semiconductor device according toclaim 13, wherein the end or side surfaces of the wall parts have aconvex or concave part for positioning.
 15. The semiconductor deviceaccording to claim 13, wherein the end or side surfaces of the wallparts are bonded.
 16. The semiconductor device according to claim 15,wherein the end or side surfaces of the wall parts are bonded by meltingthe surfaces.
 17. The semiconductor device according to claim 16,wherein the wall parts are made of at least thermoplastic resin and theend or side surfaces of the wall parts are bonded by melting thethermoplastic resin.
 18. The semiconductor device according to claim 12,wherein the heat radiation surfaces have at least one fin projectingtherefrom, and wherein the height hf of the fin and the height D of thewall part from the heat radiation surface have the relation hf<D. 19.The semiconductor device according to claim 12, wherein the heatradiation surfaces have at least one fin projecting therefrom, whereinthe height hf of the fin and the height D of the wall part from the heatradiation surface have the relation hf ≥D; and wherein positions of thefind on the heat radiation surfaces differ between one of the heatradiation surfaces and the other opposite heat radiation surface. 20.The semiconductor device according to claim 12, wherein the fins have aform similar to teeth of a comb projected from the heat radiationsurfaces, and wherein the fins on one of the heat radiation surfaces areplaces between the find on the other opposite heat radiation surface.21. The semiconductor device according to claim 12, wherein the sideshape of the wall part of the seal member is an inverted trapezoid. 22.The semiconductor device according to claim 9, wherein the stackedsemiconductor modules are configured as a power circuit.
 23. Thesemiconductor device according to claim 22, wherein a first bus bar anda second bus bar forming the input wiring of the power circuit arearranged in proximity and parallel to each other.
 24. The semiconductordevice according to claim 23, wherein an insulating member is interposedbetween the first bus bar and the second bus bar.
 25. The semiconductordevice according to claim 24, wherein the first bus bar and the secondbus bar are covered and sealed by the insulating member.
 26. Thesemiconductor device according to claim 9, wherein visible surfaces ofthe stacked semiconductor modules are formed as the printing surfaces ofthe semiconductor modules.
 27. The semiconductor device according toclaim 9, wherein the stacked semiconductor modules are connected to eachother by being held under pressure by cover plates arranged at the endsof the stacked semiconductor modules, and further the adjoiningsemiconductor modules are kept in contact with an O-ring so as to sealcontact portions between the semiconductor modules.
 28. A semiconductordevice comprising: a semiconductor element; a heat sink including ametal plate, thermally and electrically connected to the semiconductorelement, which transmits heat from the semiconductor and works as anelectrode; and a resin for completely covering the semiconductor elementand the heat sink as one body in such a manner as to expose a heatradiation surface of the heat sink, the resin adhering to thesemiconductor element and the heat sink without space; wherein a part ofthe resin offsetting externally from the resin is used as a part of anouter wall surface of a refrigerant path in which a refrigerant flows,the refrigerant cooling the heat radiation surface, and wherein aninsulating layer is formed on the heat radiation surface, wherein therefrigerant flows on a surface of the insulating layer, wherein therefrigerant path is an open area through which the refrigerant flows,and wherein the wall surface of the refrigerant path directly faces theopen area through which the refrigerant flows.
 29. A semiconductordevice comprising: a semiconductor element; a heat sink including ametal plate, thermally and electrically connected to the semiconductorelement, which transmits heat from the semiconductor and works as anelectrode; and a resin for completely covering the semiconductor elementand the heat sink as one body in such a manner as to expose a heatradiation surface of the heat sink, the resin adhering to thesemiconductor element and the heat sink without space; wherein a part ofthe resin offsetting externally from the resin is covered with a filmhaving corrosion resistance against the refrigerant and used as a partof an outer wall surface of a refrigerant path in which a refrigerantflows, the refrigerant cooling the heat radiation surface, wherein aninsulating layer is formed on the heat radiation surface, and whereinthe refrigerant flows on a surface of the insulating layer.
 30. Asemiconductor device comprising: a semiconductor element; a heat sinkthermally connected to the semiconductor element; and a resin forcompletely covering the semiconductor element and the heat sink as onebody in such a manner as to expose a heat radiation surface of the heatsink the resin adhering to the semiconductor element and the heat sinkwithout space; wherein a part of the resin offsetting externally fromthe resin is covered with a film having corrosion resistance against therefrigerant and used as a part of an outer wall surface of a refrigerantpath in which a refrigerant flows, the refrigerant cooling the heatradiation surface, and wherein the refrigerant flows on the exposedradiation surface of the heat sink.
 31. The semiconductor deviceaccording to claim 30, wherein the heat radiation surface is a metal.32. The semiconductor device according to claim 30, wherein the heatradiation surface is a metal coated with an insulator.
 33. Thesemiconductor device according to claim 32, wherein the heat radiationsurface is formed as the surface of the insulating layer on the surfaceof the metal.
 34. The semiconductor device according to claim 30,wherein electrode terminals for main current project from one side ofthe resin, and wherein control terminals are arranged on the oppositeside of the molded resin.
 35. The semiconductor device comprising aplurality of semiconductor modules, each of the semiconductor modulesaccording to claim 30, wherein the semiconductor modules are stacked andconnected so that the refrigerant paths of the semiconductor modulescommunicate with each other.
 36. The semiconductor device according toclaim 35, wherein the heat radiation surface is a metal.
 37. Thesemiconductor device according to claim 35, wherein the heat radiationsurface is a metal coated with an insulator.
 38. The semiconductordevice according to claim 35, wherein the heat radiation surfaces of thestacked semiconductor modules are placed opposite to each other.
 39. Thesemiconductor device according to claim 35, wherein the semiconductormodules are connected at end or side surfaces of the wall parts.
 40. Thesemiconductor device according to claim 39, wherein the end or sidesurfaces of the wall parts have a convex or concave part forpositioning.
 41. The semiconductor device according to claim 39, whereinthe end or side surfaces of the wall parts are bonded.
 42. Thesemiconductor device according to claim 41, wherein the end or sidesurfaces of the wall part are bonded by melting the surfaces.
 43. Thesemiconductor device according to claim 42, wherein the wall parts aremade of at least thermoplastic resin and the end or side surfaces of thewall part are bonded by melting the thermoplastic resin.
 44. Thesemiconductor device according to claim 35, wherein visible surfaces ofthe stacked semiconductor modules are formed as the printing surfaces ofthe semiconductor modules.
 45. The semiconductor device according toclaim 35, wherein the stacked semiconductor modules are connected toeach other by being held under pressure by cover plates arranged at theends of the stacked semiconductor modules, and further the adjoiningsemiconductor modules are kept in contact with an O-ring so as to sealcontact portions between the semiconductor modules.